Milking parlors with automatic cow identification systems are known in the prior art, see for example U.S. Pat. No. 5,653,192 issued to Sheen et al. and U.S. Pat. No. 5,183,008 issued to Townsend et al.
The parlor typically has an identification sensor at the entrance, which sensor includes a transmitter antenna and a receiver antenna for communicating with a transponder in an identification tag on a collar around the neck of a cow. The transponder in the identification tag includes an electronic oscillator circuit triggered by interrogating electromagnetic RF radiation from the transmitter antenna and sends back a coded identifying signal in response to the interrogating pulse, which signal is received by the receiver antenna. The coded identifying signal is an individual unique identification code identifying that particular cow.
The cows initially enter the parlor while passing serially through an entrance having the above-mentioned identification antenna system, and enter then into plural parallel milking stalls, with the first cow entering the stall in the far end of the parlor, the second cow entering the adjacent stall, etc., and the last cow entering the stall closest to the entrance.
The identification system correlates the cow passing through the identification antenna system with the stall receiving such cow. In this manner, it should be known which cows are in the respective stalls, and in turn milk production can be correlated and tracked for each cow.
A problem arises, however, when a cow passing through the entrance antenna system has lost her tag or has a malfunctioning tag, in which case there is no response signal sent back to the identification antenna system and hence no cow identified. One stall thus has an unidentified cow therein, and the computerized identification system will believe that the next cow is at such stall location.
For example, if the second cow to pass serially through the entrance has a missing tag, such cow will enter the second stall as counted from the far end of the milking parlor. However, the computerized identification system will register a second response coded signal firstly from the third cow, and hence will correlate the third cow to the second stall, i.e. the computerized identification system does not identify the second cow. Likewise, all following cows will be misidentified by one stall location, i.e. correlated to incorrect stalls.
In very small dairy farms, the above problem may not be a significant drawback because the farmers are familiar with the cows and can correct missed identifications manually. However, in large parlors, a misidentification can become a significant problem, particularly when the farmers do not know the cows well enough to correct errors manually.
In addition to absent or malfunctioning tags, misidentifications may be caused when a cow enters with her tag in an unreadable position, or may be due to electronic noise interference, etc. Even if the error or misidentification rate is low, e.g. less than 0.5%, a significant problem can arise depending upon where such error occurs in the serial flow of cows through the entrance.
For example, if one of the last cows serially entering the parlor has a missing tag, then only the few cows thereafter will also be misidentified. However, if one of the first cows serially entering the parlor has a missing tag, then each of the cows thereafter will be correlated to an incorrect stall.
For a parlor with 20 stalls in a row serving about 1000 cows and with a correct identification probability for each cow entered of 99.5%, the probability that at least one cow in a row of 20 cows is misidentified is 1-0.99520≈10%, which corresponds to about 5 of the 50 subsequent milking sessions to be performed to complete the milking of the 1000 cows. In average a misidentified cow will lead to 10 misidentifications (20/2) since all cows entered after the misidentified cow will also be misidentified. Hence, in average 50 (5*10) of the 1000 cows, or 5%, will be misidentified.
Besides, there is no knowledge of exactly which the misidentified cows are, and thus if the identification system notes that some error has occurred, i.e. due to the fact that only 19 identifications are made in a particular milking session the dairy farmer may want to omit the identification information of that session in order to be sure that all identifications actually recorded are correct. Thus, only 900 cows (1000−(5*20)), or 90%, will be certainly correctly identified. For larger parlors the correct identification probability will be even lower.
In U.S. Pat. No. 9,59,526 issued to Tucker the above-identified problem has been addressed and solved by means of an identification correction method which compares produced milk weight values and expected milk weight values in a given milking, and performs a correction by shifting at least one or more of the expected milk weight values relative to the produced milk weight values by at least one stall number, to provide accurate cow identification when there is a misidentified or unidentified cow, such as a cow having a missing identification tag.